Construction of electric heating units and connecting parts therefor



March 28, 1939. 2,152

CONSTRUCTION OF ELECTRIC HEATING UNITS AND CONNECTING PARTS THEREFOR L.. l. MIREL Filed Nov. 11, 1957 INYENTOR L Mmel Illa $1M ATTORNEY,

Patented Mar. 28, 1939 CONSTRUCTION OF ELECTRIC HEATING UNITS AND CONNECTING PARTS THERE'- FOR Louis I. Mirel, Brooklyn, N. Y., assignor to Elias Clein, Brooklyn, N. Y.

Application November 11, 1937, Serial No. 174,002

1 Claim. (Cl. 219-21) This invention relates to improvements in the construction of electric heating units and connecting parts as used in soldering implements and hair heat treating devices.

The electric heating element used in soldering irons and for heating other devices where heat is necessary, consists ordinarily of a porcelain core wrapped with resistance wire terminating in lead-in conductors, each thereof receiving its connection to a circuit wire in the course of assembling the implement. I have found the use of the lead-in conductors is no longer necessary and one of the principal objects of the present invention is to provide a direct connection between the circuit wires and the resistance element of the heating unit.

Another accepted feature in the construction of electrically heated implements of this charac ter is to enclose the connection between lead-in conductors and circuit wires with a considerable amount of tape, which forms a bulbous section disposed somewhere inside the handle portion of the implement, and which engages a restricted point in the bore of the handle to prevent the circuit wires from being accidentally pulled out of the end of the handle and the connection with the lead-in wires broken. At best this arrangement is only make-shift and temporary, because after a while the heat from the heating element dries out the tape and it soon becomes unwrapped and disconnected from the lead-in and circuit wires. Then if a pull is exerted upon the circuit wires from beyond the handle they have only the soldered connection to hold them together. As a result either the heating element is drawn from the soldering point into the stem portion and towards the handle or the connection breaks immediately and the device is rendered useless if not dangerous, because of the likelihood of the occurrence of a short circuit at the exposed ends of the circuit wires. With the foregoing in mind it is a purpose of this invention to provide a permanent and highly reliable stop for the circuit wires within the handle or grip of the implement, and I accomplish this object by forming a shoulder in the bore of the handle and by attaching a clamp or stop to the body of the circuit wires to abut the shoulder in the handle and to resist any pull on the wires to tear the cable from the implement and its connection with resistance wires of the heating element.

Almost without exception, the heated section of any soldering iron or hair heat-treating implement, which may be found on the market today,

makes use of a threaded connection between the ,may be far more dangerous to drop among loose shavings or other highly inflammable materials which are almost always present where operations of this sort are going on. According to the present invention all danger of the tips becoming accidentally disengaged from the stem or handle has been permanently overcome. It is therefore a further object of my invention to provide a novel means of permanently mounting the tip or heated section upon its supporting tube or shank.

I accomplish these objects by means of the embodiments of my invention hereinafter described in detail, set forth in the appended claim and illustratively exemplified in the accompanying drawing, in which:

Figure 1 is a substantially longitudinal sectional view of a soldering iron embodying the features of my invention;

Figure 2 is a substantially transverse sectional view taken on lines 2-2 of Figure 1;

Figure 3 is a substantially transverse sectional view taken on lines 33 of Figure 1;

Figure 4 is a sectional view on a larger scale of the connection between the resistance wire and the circuit wires arranged within the porcelain core of the heating element;

Figure 5 is a side elevational view, partly in section of the elements of the present invention applied to a hair treating device.

Referring to the drawing, Ill denotes a handle or grip, which is preferably of wood, and which is provided with an axial bore ll, having its diameter increased in two steps l2 and I3 adjacent its forward end. A shank or tubular stem I4 is mounted in the outer step I 2 of the bore and a suitable metal ferrule is applied to the end of the grip HI to embrace the shank 14.

The shank I4 is a substantially long piece of metal tubing upon the outer end of which is mounted the part to be heated, namely a copper soldering tip IE, or as in the embodiment shown in Figure 5, a hair treating head [6, and in accordance with this invention the opposite ends of the shank M are permanently attached to their respective carrying pieces, namely the handle l and tip l5, by means of a plurality of longitudinally disposed radially projecting knife edge ribs ll. These ribs I! are struck out from the outer surface of the tube and the ends thereof are driven into step l2 of the bore H in the handle and into the step I8 of the chamber I9 of the tip l5, respectively, the ribs biting into the walls of the materials and holding the three parts firmly and permanently together in an integral unit.

The heating element used in the present construction comprises a porcelain cylinder 20 hav-- ing spaced longitudinal bores 2| opening out of each end and a transverse channel 22 between the ends of the bores 2| at one end of the cyl inder. A coil of resistance wire 23 is threaded through the bores 2| and across the channel 22, the latter being sealed after receiving the wire 23 by means of an application of porcelain cement 24. The ends of the resistance wires 23 at the other end of the cylinder 20 are joined with the wires 25, by means of a spot of solder 26, as illustrated in Figure 4, of a heat insulated cable 21, the latter being brought to a point just short of the adjacent end of the porcelain 20 and joined with the latter by means of a section of porcelain cement 28. It is important to note in connection with this specific portion of the invention, that the soldered connections between the ends of the resistance wire 23 and cable wires 25, are actually disposed within the bores 2|. This is accomplished by bringing the ends of the coil of resistance wire to the outside of the bores 2| and when the connection has been made, to allow the coils to contract and draw the soldered connections inside the bores.

The cable 21 is disposed inside the bore of the shank l4 and emerges to the outside through the bore in the handle 10. It is intended that the heating element project to the full depth of the chamber IS, in the tip 15 or head IS in order to efficiently impart heat thereto, and in order to prevent the heating element from being drawn accidentally out of the chamber I and into the stem M, a coil 29 of metal is clamped about the heat insulation of the cable at a point on the latter which brings the coil 29 against the step l3 when the heating element is fully projected into the tip and thus prevents movement of the cable in an outward direction in the handle after the device has once been assembled.

Having described my invention and the manher in which the same is used what I claim and desire to secure by Letters Patent is:

As a new article of manufacture, a device comprising a handle having an axially stepped bore, a shank projecting into one step in said bore, a tip having a stepped chamber and disposed with the other end of the shank fixed in one step of said chamber, said shank being provided adjacent its ends with radial ribs which bite into the adjacent walls of the handle and tip to form a permanent connection between the parts, a heating element disposed in said tip, an insulated cable supplying electrical current to said heat ing element and projecting through said handle and shank, and a strap coiled about the insulated cable and clamped thereto, the coils of said strap seating against the shoulder formed by the second step of the handle bore to prevent Withdrawal of the cable and element from said tip and shank,

LOUIS I. MIREL. 

